barrier/CUnixEventQueue.cpp

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#include "CUnixEventQueue.h"
#include "IJob.h"
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
//
// CUnixEventQueue
//
CUnixEventQueue::CUnixEventQueue()
{
// do nothing
}
CUnixEventQueue::~CUnixEventQueue()
{
// clean up lists
clearList(m_readList);
clearList(m_writeList);
}
void CUnixEventQueue::addFileDesc(int fd,
IJob* readJob, IJob* writeJob)
{
assert(fd != -1);
assert(m_readList.count(fd) == 0 && m_writeList.count(fd) == 0);
assert(readJob != writeJob || readJob == NULL);
if (readJob)
m_readList[fd] = readJob;
if (writeJob)
m_writeList[fd] = writeJob;
}
void CUnixEventQueue::removeFileDesc(int fd)
{
assert(fd != -1);
// remove from lists
eraseList(m_readList, fd);
eraseList(m_writeList, fd);
}
void CUnixEventQueue::wait(double timeout)
{
// prepare sets
fd_set fdRead, fdWrite;
const int maxRead = prepList(m_readList, &fdRead);
const int maxWrite = prepList(m_writeList, &fdWrite);
// compute the larger of maxRead and maxWrite
const int fdMax = (maxRead > maxWrite) ? maxRead : maxWrite;
if (fdMax == -1)
return;
// prepare timeout
struct timeval* pTimeout = NULL;
struct timeval sTimeout;
if (timeout >= 0.0) {
sTimeout.tv_sec = static_cast<int>(timeout);
sTimeout.tv_usec = static_cast<int>(1000000.0 *
(timeout - sTimeout.tv_sec));
pTimeout = &sTimeout;
}
// wait
const int n = ::select(fdMax + 1, &fdRead, &fdWrite, NULL, pTimeout);
// return on error or if nothing to do
if (n <= 0)
return;
// invoke jobs
// note -- calling removeFileDesc() from a job is likely to crash the
// program because we expect all jobs with active file descriptors to
// persist for the duration of these loops.
int fd;
for (fd = 0; fd <= maxRead; ++fd)
if (FD_ISSET(fd, &fdRead)) {
assert(m_readList.count(fd) > 0);
assert(m_readList[fd] != NULL);
m_readList[fd]->run();
}
for (fd = 0; fd <= maxWrite; ++fd)
if (FD_ISSET(fd, &fdWrite)) {
assert(m_writeList.count(fd) > 0);
assert(m_writeList[fd] != NULL);
m_writeList[fd]->run();
}
}
void CUnixEventQueue::lock()
{
// do nothing
}
void CUnixEventQueue::unlock()
{
// do nothing
}
void CUnixEventQueue::signalNotEmpty()
{
// do nothing
}
void CUnixEventQueue::eraseList(List& list, int fd) const
{
List::iterator index = list.find(fd);
if (index != list.end()) {
delete index->second;
list.erase(index);
}
}
void CUnixEventQueue::clearList(List& list) const
{
for (List::const_iterator index = list.begin();
index != list.end(); ++index)
delete index->second;
list.clear();
}
int CUnixEventQueue::prepList(
const List& list, void* vfdSet) const
{
fd_set* fdSet = reinterpret_cast<fd_set*>(vfdSet);
FD_ZERO(fdSet);
int fdMax = -1;
for (List::const_iterator index = list.begin();
index != list.end(); ++index) {
const int fd = index->first;
FD_SET(fd, fdSet);
if (fd > fdMax)
fdMax = fd;
}
return fdMax;
}